1. Field of the Invention
The present invention relates to a plasma display apparatus, and more particularly, to a plasma display apparatus which reduces a noise generating in a waveform applied to a scan electrode or a sustain electrode and stabilizes address discharge by improving applying time point of a waveform applied in an address period, so that driving stability of a panel increases and a driving method thereof.
2. Description of the Background Art
In general, a plasma display apparatus comprises a plasma display panel in which barrier ribs formed between a front panel and a rear panel form a unit cell. Main discharge gas such as Neon (Ne), Helium (He), or mixed gas (Ne+He) of Neon and Helium and inert gas containing a small amount of Xenon fill each cell. When discharge is performed by a high frequency voltage, the inert gas generates vacuum ultraviolet rays and allows a phosphor formed between the barrier ribs to emit light, and thus an image is embodied. Such a plasma display apparatus is made to be thin and light, so that it has been in the spotlight as a next generation display device.
FIG. 1 illustrates a structure of a general plasma display panel.
As shown in FIG. 1, in a plasma display panel, a front substrate 100 in which a scan electrode 102, a sustain electrode 103, an upper dielectric layer 104, a protective layer 105 are formed in a front glass 101 that is a display surface in which an image is displayed and a rear substrate 110 in which a barrier rib 112, an address electrode 113, a phosphor 114, a lower dielectric layer 115 are formed in a rear glass 111 forming a rear surface are coupled to each other.
FIG. 2 illustrates a method of embodying an image gray level of a conventional plasma display apparatus.
As shown in FIG. 2, a conventional method of expressing an image gray level of a plasma display apparatus divides one frame into several subfields having the different number of light emitting. Each subfield is again sub-divided into a reset period (RPD) for initializing all cells, an address period (APD) for selecting a cell to be discharged, and a sustain period (SPD) for embodying a gray level depending on the number of discharge.
The sustain period increases in the ratio of 2n (n=0, 1, 2, 3, 4, 5, 6, 7) in each subfield. The sustain period changes in each subfield and thus a gray level of an image can be expressed by adjusting a sustain period of each subfield, that is, the number of sustain discharge.
FIG. 3 illustrates a driving waveform of the conventional plasma display apparatus.
As shown in FIG. 3, the conventional plasma display apparatus is divided into a reset period, an address period, a sustain period, and an erasing period for erasing wall charges within the discharged cell and driven.
Referring to FIG. 3, in a driving waveform of the conventional plasma display apparatus, all address waveforms applied to the address electrode in the address period and a scan waveform applied to the scan electrode are applied at the same time. If the address waveforms and the scan waveform are applied to the address electrodes (X1 to Xn) and the scan electrode (Y), respectively, at the same time point, a noise is generated in the waveform applied to the scan electrode and the waveform applied to the sustain electrode.